Enter your cable's Outer Diameter (D), Inner Diameter (d), Relative Permittivity (εr), Frequency, Cable Length, and Loss Factor (K1) to calculate the Characteristic Impedance of your Coaxial Cable — along with Capacitance and Inductance per Unit Length, Total Cable Loss, and Velocity Factor.
Characteristic Impedance
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Capacitance per Unit Length
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Inductance per Unit Length
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Total Cable Loss
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Velocity Factor
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Characteristic impedance is the ratio of voltage to current in a wave traveling along the cable. It depends on the cable's geometry and dielectric properties, typically 50Ω or 75Ω for most coaxial cables.
Cable loss increases with frequency due to skin effect and dielectric losses. Higher frequencies experience greater attenuation, which is why shorter cables or cables with better specifications are needed for high-frequency applications.
Inner diameter refers to the center conductor, while outer diameter is the overall cable dimension. The ratio between these dimensions, along with the dielectric material, determines the cable's characteristic impedance.
Relative permittivity is the dielectric constant of the insulating material between conductors. Common values are 1.0 for air, 2.1 for PTFE, and 2.3 for polyethylene. Lower values generally result in better performance.
Use the shortest practical cable length, choose cables with lower loss specifications, ensure proper impedance matching, and select cables designed for your operating frequency range.
Velocity factor is the ratio of signal propagation speed in the cable to the speed of light in vacuum, expressed as a percentage. It depends on the dielectric material and typically ranges from 66% to 85%.
Impedance matching between the cable and connected equipment minimizes reflections and signal loss. Mismatched impedances cause standing waves, reducing power transfer efficiency and potentially damaging equipment.
These calculations provide theoretical values based on ideal conditions. Actual performance may vary due to manufacturing tolerances, temperature effects, connector losses, and cable bending or aging.